EP1627871 discloses a compound of the following formula, which may be used as an intermediate to prepare a steroid hormone sulfatase inhibitor:
wherein R3 and R4 each represents hydrogen, halogen, cyano, or lower alkyl; R6 represents hydrogen or a protecting group of hydroxyl. The publication does not describe the pharmacological activity of the compound of the above formula.
EP1123926 discloses a compound of the following formula, which can be used as an intermediate to produce piperazine derivatives for treatment of central nervous system dysfunction:
wherein R1 is monocyclic or dicyclic aryl or heteroaryl; R2 is aryl or heteroaryl; A is CH2 or —CH2CH2—. The publication does not describe the pharmacological activity of the compound of the above formula.
It is discovered that the compound of the following formula (I) and pharmaceutically acceptable salt thereof may be used alone or in combination with other analgesics (in this case synergetic effect can occur) for treating acute pain, neuropathic pain or receptive nociceptive pain in mammals including human beings.